Ok. Thanks for the clarification!

Browsing install pics, I saw this one which is for sale here.

The form doesn't work in Mozilla (on Linux or Windows), but it does in IE. Anyway, they ask what kind of HU it's for. Well, I'd like to answer that it's for a Nissan factory installed Bose HU. Because I've got two HUs (the Bose and the empeg), I had to make a custom 3-way wiring harness... the connection to the Bose amp is the factory connector and that's where this "OEM-1" thing would go (between a pair of mating Nissan-Bose connectors (sounds like a type of quark).

Now I'm wishing I'd started this thread in the Install Forum. My next question is: do any of the HUs listed have wiring harnesses like the Nissan-Bose? If not, should I just pick one and then buy a pair of wiring harnesses to solder together?